1. Field of the Invention
The present invention relates to a temperature adjusting structure and a temperature adjusting method for an electric power storage device.
2. Description of Related Art
A battery assembly can be configured by stacking a plurality of batteries. At this time, a space through which cooling air flows can be formed between two each of the batteries that are arranged in a stacked manner by alternately stacking the batteries and spacers. The battery assembly is cooled when the cooling air flows through the space that is formed by the spacer (for example, Japanese Patent Application Publication No. 2012-238603 (JP 2012-238603 A)).
In a cooling structure of JP 2012-238603 A, the space through which the cooling air flows is provided by arranging the spacer between the batteries that are adjacent to each other in a stacking direction. Consequently, the battery assembly is enlarged. Considering this problem, the battery assembly is configured by stacking the batteries tightly without providing the spacer. In this case, the battery assembly can be cooled by bringing the cooling air into contact with a periphery of the battery assembly, for example, a lateral surface thereof.
However, the battery assembly cannot be cooled efficiently if the cooling air flows while simply contacting the lateral surface of the battery assembly that extends in the stacking direction. For example, in a case where the cooling air flows uniformly in the stacking direction of the battery assembly for cooling, cooling efficiency is degraded on a downstream side in a flowing direction of the cooling air. More specifically, when the cooling air that has exchanged heat with the battery positioned on an upstream side simply exchanges heat with the battery on the downstream side, the battery on the downstream side is influenced by the cooling air whose temperature has been increased on the upstream side.
Just as described, when the cooling air flows uniformly in the stacking direction, and the cooling air contacts the lateral surface of the battery assembly, a surface of the battery assembly that contacts the cooling air along the flowing direction of the cooling air (a cooling length) is extended. This causes thickening of a temperature boundary layer as the temperature boundary layer advances to the downstream. Consequently, the cooling efficiency of the battery assembly is lowered. In view of the above, it is considered to let the cooling air flow uniformly along a longitudinal direction of the lateral surface the battery assembly (the battery) that is orthogonal to the stacking direction. However, also in this case, the cooling length is extended in the flowing direction of the cooling air. Thus, due to the same reason as above, the battery assembly cannot be cooled efficiently.